Use of axial substituted phthalocyanine compoud for preparing organic thin-film transistor

ABSTRACT

This invention relates to the use of axial substituted phthalocyanine compound as a semiconductor layer between the source/drain electrodes of organic thin-film transistor. The centre ligand of the axial substituted phthalocyanine compound is an atom with 3 valences or higher, and the axial ligands are chlorine, fluorine, or oxygen which can be connected with the centre ligands of axial substituted phthalocyanine compounds. Crystalline Film with high quality can be prepared on an organic substrate from the axial substituted phthalocyanine compound using vapor deposition process. These crystalline films have high carrier mobility, rich energy level, and stable performances and are easy for integrated process. The field effect mobility and the on/off Ratio of the organic thin-film transistor are 0.01 cm 2 /Vs or more and higher than 10 5 , respectively.

FIELD OF THE INVENTION

The present invention relates to the use of axial substituted phthalocyanine compound for preparing organic thin-film transistor.

DESCRIPTION OF THE RELATED ART

Organic semiconductors with the property of high carrier mobility have application prospects in the applications of information display, integrated circuits, photovoltaic cells and sensors etc. However, at present most of the organic semiconductors show sensitivity to circumstances, which brings great difficulties to the integrated processing and application of organic electronic devices. U.S. Pat. No. 5,969,376 disclosed a p-channel organic thin-film transistor using planar metal phthalocyanines [copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc), free phthalocyanine (H2Pc), stannum phthalocyanine (SnPc)]. In 1998, Journal of the American Chemical Society (J. Am. Chem. Soc. 1998, 120, 207-208) reported an n-channel organic thin-film transistor using planar metal phthalocyanines [metal hexadecafluoro phthalocyanine (F16MPc), ferrum hexadecachloro phthalocyanine (Cl16FePc), octacyano substituted copper phthalocyanine ((CN)8CuPc)]. In 2006, Applied Physics Letter (Appl. Phys. Lett. 89, 163516 (2006)) reported an n-channel organic thin-film transistor using planar metal phthalocyanines [copper hexadecachloro phthalocyanine (Cl16CuPc)]; Chinese Patent No. 02129458.5 disclosed a p-channel organic thin-film transistor using nonplanar metal phthalocyanines [titanium oxygen phthalocyanine (TiOPc), vanadium oxygen phthalocyanine (VOPc)]. These organic semiconductors with mobility of 10-3 cm2/Vs or more are not sensitive to circumstances, work steadily and are suitable for integrated process. In order to further meet the demand of the development of organic electronic devices, it is required to further enhance and enrich the carrier mobility and the electron structures of semiconductors.

SUMMARY OF THE INVENTION

The invention aims to provide the use of axial substituted phthalocyanine compound for preparing organic thin-film transistor, and relates to the use of axial substituted phthalocyanine compound for preparing the semiconductor layer between the source and drain electrodes of organic thin-film transistor. The field effect mobility and the on/off ratio of the organic thin-film transistor using axial substituted phthalocyanine compound as semiconductor layer between the source and drain electrodes are 0.01 cm² Vs or more and higher than 10⁵, respectively.

The molecular structure schemes of axial substituted phthalocyanine compounds are shown in the FIG. 1( a) and FIG. 1( b).

In which: FIG. 1( a) shows the axial substituted phthalocyanine, M represents the centre substituted ligand, and L, L′ represent the axial ligands, wherein L and L′ can be the same or different from each other; and FIG. 1( b) shows the positions of the substituents on phenyl group: the substituted atoms of 1, 2, 3, 4, 8, 9, 10, 11, 15, 16, 17, 18, 22, 23, 24, 25 can be fluorine (F), chlorine (Cl). As an example, chloroaluminum hexadecachloro phthalocyanine (Cl₁₆AlClPc) can be mentioned.

The centre ligand of axial substituted phthalocyanine compounds is an atom with 3 valences or more, and the axial ligands are chlorine (Cl), fluorine (F), oxygen (O) which can be connected with the centre ligands of axial substituted phthalocyanine compounds.

The principle of the invention is that centre ligand and axial ligand can adjust the electron structure of axial substituted phthalocyanine.

The axial substituted phthalocyanine compound is one selected from the group consisting of indium fluorine phthalocyanine (InFPc), titanium difluorine phthalocyanine (TiF₂Pc), stannum difluorine phthalocyanine (SnF₂Pc), ferrum chlorine phthalocyanine (FeClPc), indium chlorine phthalocyanine (InClPc), gallium chlorine phthalocyanine (GaClPc), manganese chlorine phthalocyanine (MnClPc), stannum oxygen phthalocyanine (SnOPc), titanium dichlorine phthalocyanine (TiCl₂Pc), stannum dichlorine phthalocyanine (SnCl₂Pc), germanium dichlorine phthalocyanine (GeCl₂Pc), oxygen titanium hexadecafluoro phthalocyanine (F₁₆TiOPc), oxygen titanium hexadecachloro phthalocyanine (Cl₁₆TiOPc), oxygen vanadium hexadecafluoro phthalocyanine (F₁₆VOPc), oxygen vanadium hexadecachloro phthalocyanine (Cl₁₆VOPc), indium chlorine hexadecafluoro phthalocyanine (F₁₆InClPc), indium chlorine hexadecachloro phthalocyanine (Cl₁₆InClPc), stannum dichlorine hexadecafluoro phthalocyanine (F₁₆SnCl₂Pc), stannum dichlorine hexadecachloro phthalocyanine (Cl₁₆SnCl₂Pc), titanium dichlorine hexadecafluoro phthalocyanine (F₁₆TiCl₂Pc), manganese chlorine hexadecafluoro phthalocyanine (F₁₆MnClPc), aluminium chlorine hexadecafluoro phthalocyanine (F₁₆AlClPc) and aluminium chlorine hexadecachloro phthalocyanine (Cl₁₆AlClPc).

The thickness of the semiconductor layer between the source and drain electrodes of the organic thin-film transistor prepared from said axial substituted phthalocyanine compound is between 10-50 nm.

Crystalline film with high quality can be prepared on organic substrate from said axial substituted phthalocyanine compound using vapour deposition process. These crystalline films have high carrier mobility, rich energy level, stable performances and are easy for integrated process. The field effect mobility and the on/off ratio of the organic thin-film transistor using axial substituted phthalocyanine compound as the semiconductor layer between the source and drain electrodes are no less than 0.01 cm²/Vs and higher than 10⁵, respectively.

The structure of the organic thin-film transistor using axial substituted phthalocyanine compound as the semiconductor layer between the source and drain electrodes is shown in FIG. 2 in which: (1) represents substrate, (2) grid, (3) insulated gate layer, (5) and (6) source electrode and drain electrode, (7) semiconductor layer of the axial substituted phthalocyanine compounds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the molecular structure formula of the axial substituted phthalocyanine compound, in which: FIG. 1( a) shows the axial substituted phthalocyanine, M represents the centre substituted ligand, and L, L′ represent the axial ligands, wherein L and L′ can be the same or different from each other (for example, titanium dichlorine phthalocyanine (TiCl₂Pc)); and (b) shows the positions of the substituents on phenyl group: the substituted atoms of 1, 2, 3, 4, 8, 9, 10, 11, 15, 16, 17, 18, 22, 23, 24, 25 can be fluorine (F), chlorine (Cl) (for example aluminum chlorine hexadecachloro phthalocyanine (Cl₁₆AlClPc)).

FIG. 2 shows the structural scheme of the thin-film transistor, wherein, (1) represents substrate, (2) grid, (3) insulated gate layer, (5) and (6) source and drain electrodes, (7) semiconductor layer of the axial substituted phthalocyanine compound.

FIG. 3 shows the transfer characteristic curve of TiCl₂Pc.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described below in combination with appended drawings. FIG. 2 is one example of the structure using top-touch type thin-film transistor of the organic semiconductor according to the present invention.

Example 1

The tantalum pentoxide (Ta₂O₅), silicon dioxide (SiO₂) and aluminum oxide (Al₂O₃) targets, and the gold (Au) and aluminum (Al) metal electrodes used in the example are commercial products, and can be used directly. Glass substrates and plastic substrates are commercial products and can be used after cleaning. The ferrum chlorine phthalocyanine (FeClPc), titanium dichlorine phthalocyanine (TiCl₂Pc), stannum dichlorine phthalocyanine (SnCl₂Pc), indium chlorine phthalocyanine (InClPc), manganese chlorine phthalocyanine (MnClPc), gallium chlorine phthalocyanine (GaClPc), stannum oxygen phthalocyanine (SnOPc) used as the axial substituted phthalocyanine compounds in the example are commercial products and can be used after purification. Polymethyl methacrylate (PMMA) is commercial product, and was formulated into 3-0.5 wt % butanone solution for use.

A layer of metal chromium (Cr) film with the thickness of about 200 nm was plated on 7059 glass substrate or flexible plastic substrate (1) by radio frequency magnetron sputtering method, and was photoetched into grid (2); on grid (2), a layer of tantalum pentoxide (Ta₂O₅), silicon dioxide (SiO₂) or aluminum oxide (Al₂O₃) was formed as insulated gate layer (3) with the thickness of about 100 nm by magnetron sputtering method, and PMMA with the thickness of 50 nm was spinning coated on the surface of insulated gate layer (3); then semiconductor (7) with the thickness of 10 to 30 nm was grown by molecule vapour deposition process at the temperature between 25 to 250° C., source and drain electrodes (5) and (6) of gold (Au) and aluminum (Al) with the thickness of 20-50 nm were then deposited.

The source and drain electrodes, surface modification layer, and properties of the carrier mobility (cm²/Vs), types of the carriers, and on/off current ratio of thin-film transistor are listed in Table 1.

TABLE 1 Source and drain electrodes of thin-film transistor device, and properties of carrier mobility (cm²/Vs), types of the carriers and on/off current ratio of the thin-film transistor device Organic source and drain carrier carrier on/off current semiconductor electrodes mobility type ratio TiCl₂Pc Au 0.15 hole 10⁵ SnCl₂Pc Al 0.16 electron 10⁵ SnCl₂Pc Au 0.14 electron 10⁵ FeClPc Au 0.011 hole 10⁵ InClPc Au 0.025 hole 10⁵ MnClPc Au 0.011 hole 10⁵ GaClPc Au 0.010 hole 10⁵ SnOPc Al 0.017 electron 10⁵ SnOPc Au 0.020 electron 10⁵

Example 2

Tantalum pentoxide (Ta₂O₅), silicon dioxide (SiO₂) and aluminum oxide (Al₂O₃) used as targets in the example and gold (Au) and aluminum (Al) metal electrodes in the example are commercial products and can be used directly. Glass substrates and plastic substrates are commercial products and can be used after cleaning. Titanium difluorine phthalocyanine (TiF₂Pc), stannum difluorine phthalocyanine (SnF₂Pc), indium fluorine phthalocyanine (InFPc), germanium dichlorine phthalocyanine (GeCl₂Pc), oxygen titanium hexadecafluoro phthalocyanine (F₁₆TiOPc), oxygen vanadium hexadecafluoro phthalocyanine (F₁₆VOPc), indium chlorine hexadecafluoro phthalocyanine (F₁₆InClPc), manganese chlorine hexadecafluoro phthalocyanine (F₁₆MnClPc), stannum dichlorine hexadecafluoro phthalocyanine (F₁₆SnCl₂Pc), titanium dichlorine hexadecafluoro phthalocyanine (F₁₆TiCl₂Pc), aluminium chlorine hexadecafluoro phthalocyanine (F₁₆AlClPc), aluminium chlorine hexadecachloro phthalocyanine (Cl₁₆AlClPc), stannum dichlorine hexadecachloro phthalocyanine (Cl₁₆SnCl₂Pc), oxygen titanium hexadecachloro phthalocyanine (Cl₁₆TiOPc), oxygen vanadium hexadecafluoro phthalocyanine (Cl₁₆VOP_(c)), indium chlorine hexadecachloro phthalocyanine (Cl₁₆InClPc) were synthesized according to literature (Inorg. Chem. 1962, 1, 331-333; Inorganica Chimica Acta 1999, 293, 80-87).

A layer of metal chromium (Cr) film with the thickness of about 200 nm was plated on 7059 glass substrate or flexible plastic substrate (1) by radio frequency magnetron sputtering method, and was photoetched into grid (2); on grid (2) a layer of tantalum pentoxide (Ta₂O₅), silicon dioxide (SiO₂) or aluminum oxide (Al₂O₃) as insulated gate layer (3) with the thickness of about 100 nm was formed by magnetron sputtering method, and the surface of insulated gate layer (3) was modified by octadecyltrichlorosilane (hereinafter referred to as OTS), or was deposited with para-sexiphenyl (hereinafter referred to as 6P) by vacuum deposition; then semiconductor (7) with the thickness of 10 to 30 nm was grown by molecule vapor deposition process at the temperature between 25 to 250° C., and then the source and drain electrodes (5) and (6) of gold (Au) and aluminum (Al) with the thickness of 20-50 nm was also deposited.

The source and drain electrodes, surface modification layer, properties of the carrier mobility, and on/off current ratio of the thin-film transistor device are listed in Table 2.

TABLE 2 Source and drain electrodes, surface modification layer, properties of carrier mobility (cm²/Vs), carrier types and on/off current ratio of the thin-film transistor device source surface on/off Organic and drain modification carrier carrier current semiconductor electrodes layer mobility type ratio F₁₆AlClPc Al OTS 0.012 electron 10⁵ F₁₆AlClPc Al 6P 0.023 electron 10⁵ F₁₆AlClPc Au OTS 0.010 electron 10⁵ F₁₆AlClPc Al 6P 0.017 electron 10⁵ F₁₆MnClPc Al OTS 0.016 electron 10⁵ F₁₆MnClPc Al 6P 0.014 electron 10⁵ F₁₆MnClPc Au OTS 0.012 electron 10⁵ F₁₆MnClPc Au 6P 0.021 electron 10⁵ F₁₆InClPc Al OTS 0.015 electron 10⁵ F₁₆InClPc Al 6P 0.21 electron 10⁵ F₁₆InClPc Au OTS 0.012 electron 10⁵ F₁₆InClPc Au 6P 0.27 electron 10⁵ F₁₆SnCl₂Pc Al OTS 0.010 electron 10⁵ F₁₆SnCl₂Pc Al 6P 0.11 electron 10⁵ F₁₆SnCl₂Pc Au OTS 0.013 electron 10⁵ F₁₆SnCl₂Pc Au 6P 0.24 electron 10⁵ F₁₆TiCl₂Pc Al OTS 0.011 electron 10⁵ F₁₆TiCl₂Pc Al 6P 0.021 electron 10⁵ F₁₆TiCl₂Pc Au OTS 0.017 electron 10⁵ F₁₆TiCl₂Pc Au 6P 0.26 electron 10⁵ F₁₆TiOPc Al OTS 0.11 electron 10⁵ F₁₆TiOPc Al 6P 0.20 electron 10⁵ F₁₆TiOPc Au OTS 0.21 electron 10⁵ F₁₆TiOPc Au 6P 0.43 electron 10⁵ F₁₆VOPc Al OTS 0.12 electron 10⁵ F₁₆VOPc Al 6P 0.17 electron 10⁵ F₁₆VOPc Au OTS 0.23 electron 10⁵ F₁₆VOPc Au 6P 0.39 electron 10⁵ Cl₁₆SnCl₂Pc Al OTS 0.012 electron 10⁵ Cl₁₆SnCl₂Pc Al 6P 0.017 electron 10⁵ Cl₁₆SnCl₂Pc Au OTS 0.023 electron 10⁵ Cl₁₆SnCl₂Pc Au 6P 0.17 electron 10⁵ Cl₁₆AlClPc Al OTS 0.014 electron 10⁵ Cl₁₆AlClPc Al 6P 0.022 electron 10⁵ Cl₁₆AlClPc Au OTS 0.013 electron 10⁵ Cl₁₆AlClPc Au 6P 0.017 electron 10⁵ Cl₁₆InClPc Al OTS 0.015 electron 10⁵ Cl₁₆InClPc Al 6P 0.019 electron 10⁵ Cl₁₆InClPc Au OTS 0.16 electron 10⁵ Cl₁₆InClPc Au 6P 0.21 electron 10⁵ Cl₁₆VOPc Al OTS 0.010 electron 10⁵ Cl₁₆VOPc Al 6P 0.073 electron 10⁵ Cl₁₆VOPc Au OTS 0.042 electron 10⁵ Cl₁₆VOPc Au 6P 0.37 electron 10⁵ Cl₁₆TiOPc Al OTS 0.012 electron 10⁵ Cl₁₆TiOPc Al 6P 0.012 electron 10⁵ Cl₁₆TiOPc Au OTS 0.016 electron 10⁵ Cl₁₆TiOPc Au 6P 0.023 electron 10⁵ SnF₂Pc Al OTS 0.010 electron 10⁵ SnF₂Pc Al 6P 0.018 electron 10⁵ SnF₂Pc Au OTS 0.051 electron 10⁵ SnF₂Pc Au 6P 0.074 electron 10⁵ TiF₂Pc Al OTS 0.012 electron 10⁵ TiF₂Pc Al 6P 0.025 electron 10⁵ TiF₂Pc Au OTS 0.042 electron 10⁵ TiF₂Pc Au 6P 0.085 electron 10⁵ InFPc Al OTS 0.017 electron 10⁵ InFPc Al 6P 0.024 electron 10⁵ InFPc Au OTS 0.031 electron 10⁵ InFPc Au 6P 0.077 electron 10⁵ GeCl₂Pc Au OTS 0.061 hole 10⁵ GeCl₂Pc Au 6P 0.090 hole 10⁵

The present invention is not limited to the examples described above. Generally, the organic transistor disclosed in the present invention can be made into components in two dimensional or three dimensional integrated devices. These integrated devices can be used in the applications of flexible integrated circuits, active matrix display etc. The components using organic thin-film transistor according to the present invention can be processed at low temperature. 

1. A method for preparing organic thin-film transistor, comprising preparing a semiconductor layer between source and drain electrodes of the organic thin-film transistor using an axial-substituted phthalocyanine compound, wherein the centre ligand of said axial substituted phthalocyanine compound is an atom with 3 valences or higher, and the axial ligands are chlorine, fluorine, or oxygen which can be connected with the centre ligand of axial substituted phthalocyanine compounds; said axial substituted phthalocyanine compound is shown by the following formula:

wherein, M represents the centre substituted ligand, and L, L′ represent the axial ligands.
 2. The method according to claim 1, wherein said axial substituted phthalocyanine compound is one selected from the group consisting of indium fluorine phthalocyanine, titanium difluorine phthalocyanine, stannum difluorine phthalocyanine, ferrum chlorine phthalocyanine, indium chlorine phthalocyanine, gallium chlorine phthalocyanine, manganese chlorine phthalocyanine, stannum oxygen phthalocyanine, titanium dichlorine phthalocyanine, stannum dichlorine phthalocyanine, germanium dichlorine phthalocyanine, oxygen titanium hexadecafluoro phthalocyanine, oxygen titanium hexadecachloro phthalocyanine, oxygen vanadium hexadecafluoro phthalocyanine, oxygen vanadium hexadecachloro phthalocyanine, indium chlorine hexadecafluoro phthalocyanine, indium chlorine hexadecachloro phthalocyanine, stannum dichlorine hexadecafluoro phthalocyanine, stannum dichlorine hexadecachloro phthalocyanine, titanium dichlorine hexadecafluoro phthalocyanine, manganese chlorine hexadecafluoro phthalocyanine, aluminium chlorine hexadecafluoro phthalocyanine and aluminium chlorine hexadecachloro phthalocyanine.
 3. The method to claim 1, wherein the thickness of said semiconductor layer between the source and drain electrodes of the organic thin-film transistor is between 10-50 nm. 